From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 706E79000BD for ; Tue, 27 Sep 2011 07:28:16 -0400 (EDT) Date: Tue, 27 Sep 2011 13:28:10 +0200 From: Michal Hocko Subject: Re: [patch 2/2]vmscan: correctly detect GFP_ATOMIC allocation failure Message-ID: <20110927112810.GA3897@tiehlicka.suse.cz> References: <1317108187.29510.201.camel@sli10-conroe> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317108187.29510.201.camel@sli10-conroe> Sender: owner-linux-mm@kvack.org List-ID: To: Shaohua Li Cc: Andrew Morton , mel , Rik van Riel , linux-mm On Tue 27-09-11 15:23:07, Shaohua Li wrote: > has_under_min_watermark_zone is used to detect if there is GFP_ATOMIC allocation > failure risk. For a high end_zone, if any zone below or equal to it has min > matermark ok, we have no risk. But current logic is any zone has min watermark > not ok, then we have risk. This is wrong to me. This, however, means that we skip congestion_wait more often as ZONE_DMA tend to be mostly balanced, right? This would mean that kswapd could hog CPU more. Does this fix any particular problem you are seeing? > > Signed-off-by: Shaohua Li > --- > mm/vmscan.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > Index: linux/mm/vmscan.c > =================================================================== > --- linux.orig/mm/vmscan.c 2011-09-27 15:09:29.000000000 +0800 > +++ linux/mm/vmscan.c 2011-09-27 15:14:45.000000000 +0800 > @@ -2463,7 +2463,7 @@ loop_again: > > for (priority = DEF_PRIORITY; priority >= 0; priority--) { > unsigned long lru_pages = 0; > - int has_under_min_watermark_zone = 0; > + int has_under_min_watermark_zone = 1; > > /* The swap token gets in the way of swapout... */ > if (!priority) > @@ -2594,9 +2594,10 @@ loop_again: > * means that we have a GFP_ATOMIC allocation > * failure risk. Hurry up! > */ > - if (!zone_watermark_ok_safe(zone, order, > + if (has_under_min_watermark_zone && > + zone_watermark_ok_safe(zone, order, > min_wmark_pages(zone), end_zone, 0)) > - has_under_min_watermark_zone = 1; > + has_under_min_watermark_zone = 0; > } else { > /* > * If a zone reaches its high watermark, > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: email@kvack.org -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org